Unilateral tonic pupil in spinocerebellar ataxia without brainstem atrophy

We report a case of unilateral tonic pupil in spinocerebellar ataxia without brainstem atrophy in a 42year-old man. On neurological examination, he showed cerebellar symptoms and unilateral tonic pupil. Deep tendon reflexes were normal except for brisk patellar tendon reflexes. Brain MRI demonstrated cerebellar atrophy only. There was neither orthostatic hypotension nor bowel and bladder failure. The right pupil constricted from 5.0 mm to 1.7 mm 60 minutes after 0.125% pilocarpine administration, whereas the left pupil did not change, remaining at 3.7 mm. Although it is not proven that tonic pupil is causally related to spinocerebellar ataxia, physicians must remain aware of spinocerebellar ataxia as a disease that can demonstrate tonic pupil. Neurology Asia 2007; 12 : 131 – 133 Address correspondence to: Shiroh Miura, Division of Respirology, Neurology and Rheumatology, Department of Medicine, Kurume University School of Medicine, 67 Asahimachi, Kurume City, Fukuoka 830-0011, Japan. E-mail: [email protected] INTRODUCTION Tonic pupil is due to postganglionic parasympathetic denervation of the iris sphincter associated with a variety of neurological diseases, and is usually associated with areflexia or hyporeflexia. Idiopathic cerebellar ataxia (IDCA) with additional extracerebellar features not corresponding to multiple system atrophy (IDCA-P) includes the autonomic disorder such as bladder dysfunction or constipation.1 To date, there are no reports of tonic pupil associated with IDCA-P. We describe here the first patient of spinocerebellar ataxia without brainstem atrophy who showed a unilateral tonic pupil without hyporeflexia.